AUDIO AND VISUAL SYSTEM(for Radio Receiver Type) Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DTC Code DTC Name
Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the radio receiver assembly.

The Automatic Sound Levelizer (ASL) function automatically adjusts the audio system volume level in order to compensate for increased vehicle noise (vehicle noise tends to increase as vehicle speed increases). The ASL adjusts the volume level based upon vehicle speed signals sent from the combination meter assembly.

Tip:

  • A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter assembly. The signal is changed to a pulse signal at the transistor in the combination meter assembly. Each ECU controls its respective system based on this pulse signal.

  • If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the following diagram will not operate normally.

WIRING DIAGRAM

E292674E01

PROCEDURE

  1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

    1. Check the output waveform.

      E267543C06

      *a

      Component with harness connected

      (Combination Meter Assembly)

      -

      -

      1. Remove the combination meter assembly with the connector still connected.

      2. Connect an oscilloscope to terminal E12-22 (+S) and body ground.

      3. Turn the ignition switch to ON.

      4. Turn a wheel slowly.

      5. Check the signal waveform according to the condition(s) in the table below.

        Item

        Condition

        Measurement terminal

        E12-22 (+S) - Body ground

        Tool setting

        5 V/DIV., 20 ms./DIV.

        Vehicle condition

        Wheel being rotated

        OK

        The waveform is similar to that shown in the illustration.

        Tip:

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

    Result

    Proceed to

    OK

    NG
    NG

    GO TO METER / GAUGE SYSTEM

    Click here

    OK

  2. INSPECT RADIO RECEIVER ASSEMBLY (INPUT WAVEFORM)

    1. Check the output waveform.

      E265791C14

      *a

      Component with harness connected

      (Radio Receiver Assembly)

      -

      -

      1. Remove the radio receiver assembly with the connector still connected.

      2. Connect an oscilloscope to terminal E55-16 (SPD) and body ground.

      3. Turn the ignition switch to ON.

      4. Turn a wheel slowly.

      5. Check the signal waveform according to the condition(s) in the table below.

        Item

        Condition

        Measurement terminal

        E55-16 (SPD) - Body ground

        Tool setting

        5 V/DIV., 20 ms./DIV.

        Vehicle condition

        Wheel being rotated

        OK

        The waveform is similar to that shown in the illustration.

        Tip:

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE RADIO RECEIVER ASSEMBLY

    Click here

    NG

  3. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - NO. 5 JUNCTION CONNECTOR)

    1. Disconnect the E55 radio receiver assembly connector.

    2. Disconnect the E22 No. 5 junction connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      E55-16 (SPD) - E22-7

      Always

      Below 1 Ω

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - NO. 5 JUNCTION CONNECTOR)

    1. Disconnect the E12 combination meter assembly connector.

    2. Disconnect the E22 No. 5 junction connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      E12-22 (+S) - E22-5

      Always

      Below 1 Ω

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE NO. 5 JUNCTION CONNECTOR

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR